Mike's Spool Holder
I was really liking the roller type spool holders, but once the filament got low it would fall off.
This is my new favorite spool holder.
I printed in ABS at 50% fill (you might want to go higher), then glued it together with acetone. Screw holes are included.
It uses two bearings: http://www.amazon.com/gp/product/B002BBGTK6
1.stl is the only part that needs supports. Attach the bearings with two M8 bolts.